1. Technical Field
The present invention relates to projection display devices and methods for controlling the projection display device.
2. Related Art
A projection display device (a projector) having an opening and closing mechanism (a shutter) that opens and closes an exhaust port (an opening for ventilation) and uses a drive motor as a drive source of the opening and closing mechanism has been proposed (see, for example, Japanese Patent No. 3,453,775 (Patent Documents 1) and JP-A-2009-98481 (Patent Document 2)). The projection display device of this kind generally operates by using an external power source as operating power, and is operable when a power cable extending from the projection display device is connected to a receptacle via a plug.
In the configuration of Patent Document 1, when the plug is disconnected, the opening and closing mechanism cannot be driven and therefore the exhaust port cannot be closed. If the exhaust port is not closed, dust and insects enter the device. Moreover, in the existing configuration, since the opening and closing mechanism is driven by the drive motor, it takes time before the exhaust port is completely closed, and the user has to wait for the exhaust port to be completely closed. In this case, there is a possibility that the user disconnects the plug before the exhaust port is completely closed and the exhaust port is left open.
On the other hand, in Patent Document 2, a configuration is described in which power is supplied from a standby power source section when an interruption of an external power source is detected and, after cooling is performed by a cooling device for a predetermined time, the exhaust port is closed.
However, in the configuration of Patent Document 2, it is necessary to supply power to the cooling device after the interruption of the external power source. As a result, there is a possibility that power is consumed before the exhaust port is closed, making it impossible to close the exhaust port. Moreover, the standby power source section increases in capacity.
A state in which the exhaust port is not closed when the external power source is interrupted is an undesirable state for, in particular, a projection display device to which dust prevention measures are applied so that the device can be used in a dust-prone region, that is, a dustproof projection display device (a dustproof projector).